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Homogenization requires 3 to 5 minutes. Drying the sample requires one to two hours. Grinding and <br /> sieving requires another 10 to 15 minutes per sample. Lastly, when grinding and sieving is <br /> conducted, time must be allotted to decontaminate the mortars, pestles, and sieves. Drying and <br /> grinding the samples and decontamination procedures will often dictate that an extra person be on <br /> site so that the analyst can keep up with the sample collection crew. The cost of requiring an extra <br /> person on site to prepare samples must be balanced with the gain in data quality and sample <br /> throughput. <br /> 13.8 The following documents may provide additional guidance and insight on this method <br /> and technique: <br /> 13.8.1 Hewitt, A.D. 1994. "Screening for Metals by X-ray Fluorescence <br /> Spectrometry/Response Factor/Compton Ka Peak Normalization Analysis." American <br /> Environmental Laboratory. Pages 24-32. <br /> 13.8.2 Piorek, S., and J.R. Pasmore. 1993. "Standardless, In Situ Analysis of <br /> Metallic Contaminants in the Natural Environment With a PC-Based, High Resolution Portable <br /> X-Ray Analyzer." Third International Symposium on Field Screening Methods for Hazardous <br /> Waste and Toxic Chemicals. Las Vegas, Nevada. February 24-26, 1993. Volume 2, Pages <br /> 1135-1151. <br /> 14.0 POLLUTION PREVENTION <br /> 14.1 Pollution prevention encompasses any technique that reduces or eliminates the quantity <br /> and/or toxicity of waste at the point of generation. Numerous opportunities for pollution prevention <br /> exist in laboratory operation. The EPA has established a preferred hierarchy of environmental <br /> management techniques that places pollution prevention as the management option of first choice. <br /> Whenever feasible, laboratory personnel should use pollution prevention techniques to address their <br /> waste generation. When wastes cannot be feasibly reduced at the source, the Agency recommends <br /> recycling as the next best option. <br /> 14.2 For information about pollution prevention that may be applicable to laboratories and <br /> research institutions consult Less is Better. Laboratory Chemical management for Waste Reduction <br /> available from the American Chemical Society's Department of Government Relations and Science <br /> Policy, 1155 16th Street N.W., Washington D.C. 20036, (202) 872-4477. <br /> 15.0 WASTE MANAGEMENT <br /> The Environmental Protection Agency requires that laboratory waste management practices <br /> be conducted consistent with all applicable rules and regulations. The Agency urges laboratories <br /> to protect the air, water, and land by minimizing and controlling all releases from hoods and bench <br /> operations, complying with the letter and spirit of any sewer discharge permits and regulations, and <br /> by complying with all solid and hazardous waste regulations, particularly the hazardous waste <br /> identification rules and land disposal restrictions. For further information on waste management, <br /> consult The Waste Management Manual for Laboratory Personnel available from the American <br /> Chemical Society at the address listed in Sec. 14.2. <br /> 16.0 REFERENCES <br /> b <br /> 1. Metorex. X-MET 920 User's Manual. <br /> CD-ROM 6200 - 21 Revision 0 <br /> January 1998 <br />